ElmwoodBuffalo, I see you're somewhat new to tpf.
I can't speak for the Birkin as I don't own one, but both my Kelly's (one from 2008 - bought in a Boutique; one from 1973), have NO stitching under the lock unless you're referring to the stitching on the bottom of the flap through which the turnbuckle fastens. I put my bags under a magnifying light (like one uses for needlework), and ALL my stitches are what you refer to as "right slant" - the entire bag. We've all seen too many videos made by Hermes showing how the stitching is done on a Kelly or a Birkin for me to believe that these stitches are made by a hand-guided machine. I have no idea what the your source is for this "right slant/left slant" thing, but I don't believe it is correct.
I can't speak for the Birkin as I don't own one, but both my Kelly's (one from 2008 - bought in a Boutique; one from 1973), have NO stitching under the lock unless you're referring to the stitching on the bottom of the flap through which the turnbuckle fastens. I put my bags under a magnifying light (like one uses for needlework), and ALL my stitches are what you refer to as "right slant" - the entire bag. We've all seen too many videos made by Hermes showing how the stitching is done on a Kelly or a Birkin for me to believe that these stitches are made by a hand-guided machine. I have no idea what the your source is for this "right slant/left slant" thing, but I don't believe it is correct.